The conventional structure of an automotive upholstery or interior component such as an automotive door trim, a rear corner trim or the like used on the interior of an automotive body panel is now described in the following with reference to FIG. 21 by taking an example of automotive door trim. This automotive door trim 1 consists of a laminated molded assembly comprising a resin core member 2 molded into a desired contoured shape, and a surface skin member 3 integrally laminated on a front surface of the resin core member 2 and imparted with a suitable cushioning capability.
Because of the demand for ever increasingly complex three-dimensionally contoured shapes, the resin core member 2 is now typically molded by the process of mold press forming offering a favorably molding capability. To simplify the overall fabrication process, often, the surface skin member 3 is integrally joined with the resin core member 2 during the process of mold press forming the resin core member 2.
More specifically, as illustrated in FIG. 22, the surface skin member 3 is mounted on the upper die 4 for mold press forming by using set pins 4a provided therein, and after lowering the upper die 4 for mold press forming until a prescribed clearance is defined between the upper and lower dies 4 and 5, resin material 7 is supplied to the die surface of the lower die 5 for mold press forming from an injection molding device 6 via a hot runner 5a and a plurality of gates 5b branching off from the hot runner 5a.
Then, the upper and lower dies 4 and 5 are closed upon each other, and are engaged with each other so that the surface skin member 3 is integrally joined with the front surface of the resin core member 2 at the same time as the resin material 7 is mold press formed into the resin core member 2 having a prescribed shape.
However, according to this conventional process of integrally joining the resin core member 2 and the surface skin member 3 and completing the laminated molded assembly by mold press forming, the surface skin member 3 may not be able to closely follow the highly complicated surface contour of the resin core member 2 during the process of mold press forming, and the surface skin member 3 may get damaged in some places. Such damages to the surface skin member 3 leads to the leaking of the resin material therefrom, and the assembly involving such damages to the surface skin member is obviously unacceptable as a finished product.
According to this method, since vacuum is created between the upper die 4 and the molded assembly when lifting the upper die 4 upon completion of the step of mold press forming, as a measure for preventing the molded assembly from being pulled by the upper die 4, the lower die 5 is sometimes provided with vacuum suction holes 8 for retaining the molded assembly on the lower die 5 by vacuum suction after opening up the die assembly as illustrated in FIG. 23.
Further, as a method for retaining the molded assembly on the lower die 5 when opening up the die assembly, the resin core member 2 may be provided with undercut portions 2a in the resin core member 2 as illustrated in FIG. 24 so that the molded assembly may be retained by the lower die 5 after completion of the step of mold press forming by engaging the molded assembly with the lower die 5 by using the undercut portions 2a of the resin core member 2. In such a situation, the undercut portions 2a, for instance serving as seat portions for clips and other fasteners, may get damaged in the process.
However, when a vacuum suction mechanism is used as illustrated in FIG. 23, due to the provision of a hot runner 5a and gates 5b for supplying molten resin from an injection molding device, there is a severe restriction on the layout of the vacuum suction holes 7, and the work involved in providing the piping for the vacuum suction holes is substantial.
Further, the need for large additional equipment such as a vacuum pump will increase the cost, and the selection of the material to be molded will be limited.
According to the method of providing undercut portions 2a in the resin core member as illustrated in FIG. 24, these undercut portions 2a will create such problems as hindering the effort to remove the molded product from the lower die 2a, and increasing the possibility of deforming and damaging the molded product when removing the molded product from the lower die 5. Further, the need for the undercut portions 2a leads to the increase in the weight of the resin core member 2, and is detrimental to the desire to reduce the weight of the molded product.
In either of these conventional methods, since the force retaining the molded product to the lower die 5 is so small that the speed of opening the die assembly needs to be kept low, and the time required for the overall fabrication process tends to be increased.